/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard;

import java.io.File;
import java.net.URISyntaxException;
import java.net.URL;

/**
 * This class checks whether the output is up to date.
 *
 * @author Eric Lafortune
 */
public class UpToDateChecker {
    private final Configuration configuration;

    /**
     * Creates a new UpToDateChecker with the given configuration.
     */
    public UpToDateChecker(Configuration configuration) {
        this.configuration = configuration;
    }

    /**
     * Returns whether the output is up to date, based on the modification times of the input jars, output jars, and
     * library jars (or directories).
     */
    public boolean check() {
        try {
            ModificationTimeChecker checker = new ModificationTimeChecker();

            checker.updateInputModificationTime(configuration.lastModified);

            ClassPath programJars = configuration.programJars;
            ClassPath libraryJars = configuration.libraryJars;

            // Check the dates of the program jars, if any.
            if (programJars != null) {
                for (int index = 0; index < programJars.size(); index++) {
                    // Update the input and output modification times.
                    ClassPathEntry classPathEntry = programJars.get(index);

                    checker.updateModificationTime(classPathEntry.getFile(), classPathEntry.isOutput());
                }
            }

            // Check the dates of the library jars, if any.
            if (libraryJars != null) {
                for (int index = 0; index < libraryJars.size(); index++) {
                    // Update the input modification time.
                    ClassPathEntry classPathEntry = libraryJars.get(index);

                    checker.updateModificationTime(classPathEntry.getFile(), false);
                }
            }

            // Check the dates of the auxiliary input files.
            checker.updateInputModificationTime(configuration.applyMapping);
            checker.updateInputModificationTime(configuration.obfuscationDictionary);
            checker.updateInputModificationTime(configuration.classObfuscationDictionary);
            checker.updateInputModificationTime(configuration.packageObfuscationDictionary);

            // Check the dates of the auxiliary output files.
            checker.updateOutputModificationTime(configuration.printSeeds);
            checker.updateOutputModificationTime(configuration.printUsage);
            checker.updateOutputModificationTime(configuration.printMapping);
            checker.updateOutputModificationTime(configuration.printConfiguration);
            checker.updateOutputModificationTime(configuration.dump);
        } catch (IllegalStateException e) {
            // The output is outdated.
            return false;
        }

        System.out.println("The output seems up to date");

        return true;
    }

    /**
     * This class maintains the modification times of input and output. The methods throw an IllegalStateException if
     * the output appears outdated.
     */
    private static class ModificationTimeChecker {

        private long inputModificationTime = Long.MIN_VALUE;
        private long outputModificationTime = Long.MAX_VALUE;

        /**
         * Updates the input modification time based on the given file or directory (recursively).
         */
        public void updateInputModificationTime(URL url) {
            if (url != null && url.getProtocol().equals("file")) {
                try {
                    updateModificationTime(new File(url.toURI()), false);
                } catch (URISyntaxException ignore) {
                }
            }
        }

        /**
         * Updates the input modification time based on the given file or directory (recursively).
         */
        public void updateInputModificationTime(File file) {
            if (file != null) {
                updateModificationTime(file, false);
            }
        }

        /**
         * Updates the input modification time based on the given file or directory (recursively).
         */
        public void updateOutputModificationTime(File file) {
            if (file != null && file.getName().length() > 0) {
                updateModificationTime(file, true);
            }
        }

        /**
         * Updates the specified modification time based on the given file or directory (recursively).
         */
        public void updateModificationTime(File file, boolean isOutput) {
            // Is it a directory?
            if (file.isDirectory()) {
                // Ignore the directory's modification time; just recurse on
                // its files.
                File[] files = file.listFiles();

                // Still, an empty output directory is probably a sign that it
                // is not up to date.
                if (files.length == 0 && isOutput) {
                    updateOutputModificationTime(Long.MIN_VALUE);
                }

                for (int index = 0; index < files.length; index++) {
                    updateModificationTime(files[index], isOutput);
                }
            } else {
                // Update with the file's modification time.
                updateModificationTime(file.lastModified(), isOutput);
            }
        }

        /**
         * Updates the specified modification time.
         */
        public void updateModificationTime(long time, boolean isOutput) {
            if (isOutput) {
                updateOutputModificationTime(time);
            } else {
                updateInputModificationTime(time);
            }
        }

        /**
         * Updates the input modification time.
         */
        public void updateInputModificationTime(long time) {
            if (inputModificationTime < time) {
                inputModificationTime = time;

                checkModificationTimes();
            }
        }

        /**
         * Updates the output modification time.
         */
        public void updateOutputModificationTime(long time) {
            if (outputModificationTime > time) {
                outputModificationTime = time;

                checkModificationTimes();
            }
        }

        private void checkModificationTimes() {
            if (inputModificationTime > outputModificationTime) {
                throw new IllegalStateException("The output is outdated");
            }
        }
    }
}
